2,431 research outputs found
Tri-tert-butylphosphonium hydroxytris(pentafluorophenyl)borate
The ionic title compound, C12H28P+·C18HBF15O−, was obtained by the stoichiometric reaction of tBu3P, B(C6F5)3 and water in toluene. A weak P—H⋯O hydrogen bond is observed in the crystal structure
Infrared spectroscopy of intermediate mass young stellar objects
In this paper we present Spitzer Infrared Spectrograph spectroscopy for 14
intermediate-mass young stellar objects. We use Spitzer spectroscopy to
investigate the physical properties of these sources and their environments.
Our sample can be divided into two types of objects: young isolated, embedded
objects with spectra that are dominated by ice and silicate absorption bands,
and more evolved objects that are dominated by extended emission from
polycyclic aromatic hydrocarbons (PAHs) and pure H2 rotational lines. We are
able to constrain the illuminating FUV fields by classifying the PAH bands
below 9micron. For most of the sources we are able to detect several atomic
fine structure lines. In particular, the [NeII] line appearing in two regions
could originate from unresolved photodissociation regions (PDRs) or J-shocks.
We relate the identified spectral features to observations obtained from NIR
through submillimeter imaging. The spatial extent of several H2 and PAH bands
is matched with morphologies identified in previous Spitzer/IRAC observations.
This also allows us to distinguish between the different H2 excitation
mechanisms. In addition, we calculate the optical extinction from the silicate
bands and use this to constrain the spectral energy distribution fit, allowing
us to estimate the masses of these YSOs.Comment: 21 pages, 26 figures, accepted to Ap
Treatment of bone tumours by radiofrequency thermal ablation
Radiofrequency thermal ablation (RFTA) is considered the treatment of choice for osteoid osteomas, in which it has long been safely used. Other benign conditions (chondroblastoma, osteoblastoma, giant cell tumour, etc.) can also be treated by this technique, which is less invasive than traditional surgical procedures. RFTA ablation is also an option for the palliation of localized, painful osteolytic metastatic and myeloma lesions. The reduction in pain improves the quality of life of patients with cancer, who often have multiple morbidities and a limited life expectancy. In some cases, these patients are treated with RFTA because conventional therapies (surgery, radiotherapy, chemotherapy, etc.) have been exhausted. In other cases, it is combined with conventional therapies or other percutaneous treatments, e.g., cementoplasty, offering faster pain relief and bone strengthening. A multidisciplinary approach to the management of these patients is recommended to select the optimal treatment, including orthopaedic surgeons, neurosurgeons, medical and radiation oncologists and interventional radiologists
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Constraints on Marine Isotope Stage 3 and 5 Sea Level from the Flooding History of the Karimata Strait in Indonesia
Global mean sea level (GMSL) during intermediate interglacial Marine Isotope Stage 3 (MIS 3) (60–26 ka) has proven difficult to constrain. Paleo-sea level estimates based on ice margin, modeling, and paleo-shoreline reconstructions indicate that MIS 3 GMSL was substantially higher than reconstructed from deep-ocean benthic foraminifera oxygen isotope (δ¹⁸O) and coral records, implying much smaller ice sheets during MIS 3. Here, we use the δ¹⁸O and Mg/Ca chemistry of surface and thermocline dwelling foraminifera in the Sulu Sea in the western Pacific margin to estimate relative changes of the influx of South China Sea surface flow through the Sulu Sea over the last 140 ka. We show that this South China Sea throughflow is controlled in part by changes in GMSL modulating the depth of the 36 m deep Karimata Strait at the southern end of the South China Sea. We constrain maximum allowable GMSL at the beginning and end of MIS 3 to −22 ± 6 and −29 ± 5 m, respectively, and minimum allowable GMSL during interglacial stages MIS 5c and 5a (117–72 ka) to range from −3 ± 8 to −8 ± 8 m and −11 ± 7 to −12 ± 7 m, respectively. Our results constrain MIS 3 GMSL, but do not rule out higher MIS 3 ice margin, modeling, and paleo-shoreline-based MIS 3 GMSL estimates or lower coral and seawater δ¹⁸O-based estimates. Our results favor the highest MIS 5a and 5c GMSL estimates and confirm that the Sunda Shelf served as a land-bridge for human and megafauna migration during MIS 3 when humans first arrived in Borneo
Stance Polarity in Political Debates: a Diachronic Perspective of Network Homophily and Conversations on Twitter
[EN] In the last decade, social media gained a very significant role in public debates, and despite the many intrinsic difficulties of analyzing data streaming from on-line platforms that are poisoned by bots, trolls, and low-quality information, it is undeniable that such data can still be used to test the public opinion and overall mood and to investigate how individuals communicate with each other. With the aim of analyzing the debate in Twitter on the 2016 referendum on the reform of the Italian Constitution, we created an Italian annotated corpus for stance detection for automatically estimating the stance of a relevant number of users. We take into account a diachronic perspective to shed lights on users' opinion dynamics. Furthermore, different types of social network communities, based on friendships, retweets, quotes, and replies were investigated, in order to analyze the communication among users with similar and divergent viewpoints. We observe particular aspects of users' behavior. First, our analysis suggests that users tend to be less explicit in expressing their stances after the outcome of the vote; simultaneously, users who exhibit a high number of cross-stance relations tend to become less polarized or to adopt a more neutral style in the following phase of the debate. Second, despite social media networks are generally aggregated in homogeneous communities, we highlight that the structure of the network can strongly change when different types of social relations are considered. In particular, networks defined by means of reply-to messages exhibit inverse homophily by stance, and users use more often replies for expressing diverging opinions, instead of other forms of communication. Interestingly, we also observe that the political polarization increases forthcoming the election and decreases after the election day.The work of Viviana Patti and Giancarlo Ruffo was partially funded by the Fondazione CRT under research project the Hate Speech and Social Media (2016.0688), and the "Progetto di Ateneo/CSP 2016" under research project "Immigrants, Hate and Prejudice in Social Media" (S1618_L2_BOSC_01). The work of Paolo Rosso was partially funded by the Spanish MICINN under the research project "MISMIS-FAKEnHATE on Misinformation and Miscommunication in social media: FAKE news and HATE speech" (PGC2018-096212-B-C31).Lai, M.; Tambuscio, M.; Patti, V.; Ruffo, G.; Rosso, P. (2019). Stance Polarity in Political Debates: a Diachronic Perspective of Network Homophily and Conversations on Twitter. Data & Knowledge Engineering. 124:1-20. https://doi.org/10.1016/j.datak.2019.101738S12012
Transcranial direct current stimulation facilitates motor learning post-stroke: a systematic review and meta-analysis.
Transcranial direct current stimulation (tDCS) is an attractive protocol for stroke motor recovery. The current systematic review and meta-analysis investigated the effects of tDCS on motor learning post-stroke. Specifically, we determined long-term learning effects by examining motor improvements from baseline to at least 5 days after tDCS intervention and motor practise. 17 studies reported long-term retention testing (mean retention interval=43.8 days; SD=56.6 days) and qualified for inclusion in our meta-analysis. Assessing primary outcome measures for groups that received tDCS and motor practise versus sham control groups created 21 valid comparisons: (1) 16 clinical assessments and (2) 5 motor skill acquisition tests. A random effects model meta-analysis showed a significant overall effect size=0.59 (p<0.0001; low heterogeneity, T(2)=0.04; I(2)=22.75%; and high classic fail-safe N=240). 4 moderator variable analyses revealed beneficial effects of tDCS on long-term motor learning: (1) stimulation protocols: anodal on the ipsilesional hemisphere, cathodal on the contralesional hemisphere, or bilateral; (2) recovery stage: subacute or chronic stroke; (3) stimulation timing: tDCS before or during motor practise; and (4) task-specific training or conventional rehabilitation protocols. This robust meta-analysis identified novel long-term motor learning effects with tDCS and motor practise post-stroke
Rapid regulation of telomere length is mediated by poly(ADP-ribose) polymerase-1
Shelterin/telosome is a multi-protein complex at mammalian telomeres, anchored to the double-stranded region by the telomeric-repeat binding factors-1 and -2. In vitro modification of these proteins by poly(ADP-ribosyl)ation through poly(ADP-ribose) polymerases-5 (tankyrases) and -1/-2, respectively, impairs binding. Thereafter, at least telomeric-repeat binding factor-1 is degraded by the proteasome. We show that pharmacological inhibition of poly(ADP-ribose) polymerase activity in cells from two different species leads to rapid decrease in median telomere length and stabilization at a lower setting. Specific knockdown of poly(ADP-ribose) polymerase-1 by RNA interference had the same effect. The length of the single-stranded telomeric overhang as well as telomerase activity were not affected. Release of inhibition led to a fast re-gain in telomere length to control levels in cells expressing active telomerase. We conclude that poly(ADP-ribose) polymerase-1 activity and probably its interplay with telomeric-repeat binding factor-2 is an important determinant in telomere regulation. Our findings reinforce the link between poly(ADP-ribosyl)ation and aging/longevity and also impact on the use of poly(ADP-ribose) polymerase inhibitors in tumor therapy
An investigation of intensity-modulated radiation therapy versus conventional two-dimensional and 3D-conformal radiation therapy for early stage larynx cancer
<p>Abstract</p> <p>Introduction</p> <p>Intensity modulated radiation therapy (IMRT) has been incorporated at several institutions for early stage laryngeal cancer (T1/T2N0M0), but its utility is controversial.</p> <p>Methods</p> <p>In three representative patients, multiple plans were generated: 1) Conventional 2D planning, with the posterior border placed at either the anterior aspect ("tight" plan) or the mid-vertebral body ("loose" plan), 2) 3D planning, utilizing both 1.0 and 0.5 cm margins for the planning target volume (PTV), and 3) IMRT planning, utilizing the same margins as the 3D plans. A dosimetric comparison was performed for the target volume, spinal cord, arytenoids, and carotid arteries. The prescription dose was 6300 cGy (225 cGy fractions), and the 3D and IMRT plans were normalized to this dose.</p> <p>Results</p> <p>For PTV margins of 1.0 cm and 0.5 cm, the D95 of the 2D tight/loose plans were 3781/5437 cGy and 5372/5869 cGy, respectively (IMRT/3D plans both 6300 cGy). With a PTV margin of 1.0 cm, the mean carotid artery dose was 2483/5671/5777/4049 cGy in the 2D tight, 2D loose, 3D, and IMRT plans, respectively. When the PTV was reduced to 0.5 cm, the the mean carotid artery dose was 2483/5671/6466/2577 cGy to the above four plans, respectively. The arytenoid doses were similar between the four plans, and spinal cord doses were well below tolerance.</p> <p>Conclusions</p> <p>IMRT provides a more ideal dose distribution compared to 2D treatment and 3D planning in regards to mean carotid dose. We therefore recommend IMRT in select cases when the treating physician is confident with the GTV.</p
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